Yarn sensing device

ABSTRACT

A yarn sensing device having a displacable load, for instance of a ball, eccentrically positioned on the axis of a rotatable yarn sensing arm. The load exerts very little tension at the normal position, that is when a yarn is present, but in the absence of a yarn the load gradually increases so that the arm tips up. With this arrangement a switch arrangement may be mounted to feed an electrical signal. Among the advantages of the device are the low tension exerted on the yarn at normal position and the remarkable stability of this device.

United States Patent [19] Parent Dec. 31, 1974 1 YARN SENSING DEVICE [75] Inventor: Edgar Parent, St. Jean, Quebec,

Canada [73] Assignee: Celanese Canada Limited, Montreal,

Quebec, Canada [22] Filed: Mar. 2, 1973 [21] Appl. No.: 337,602

[52] US. Cl..... ZOO/61.13, ZOO/61.18, ZOO/61.45 M [51] Int. Cl B6511 25/14 [58] Field of Search ZOO/61.13, 61.18, 61.45 M,

ZOO/DIG. 029; 66/161, 163; 19/25, .26;

[56] References Cited UNITED STATES PATENTS 1,662,979 '3/1928 Nelson 200/D1G. 029 3,343,008 9/1967 Bancroft.... ZOO/61.18 X 3,429,146 2/1969 Cuach.... 200/6l.18 X 3,448,228 6/1969 Munroe ZOO/61.45 M UX 3,521,265 7/1970 Bancroft ZOO/61.18 X

FOREIGN PATENTS OR APPLlCATlONS 1,042,539 6/1953 France 66/163 Primary Examiner-James R. Scott Att0rney, Agent, or Firm-Pamela D. Kasa 5 7 ABSTRACT A yarn sensing device having a displacable load, for instance of a ball, eccentrically positioned on the axis of a rotatable yarn sensing arm. The load exerts very little tension at the normal position, that is when a yarn is present, but in the absence of a yarn the load gradually increases so that the arm tips up. With this arrangement a switch arrangement may be mounted to feed an electrical signal. Among the advantages of the device are the low tension exerted on the yarn at normal position and the remarkable stability of this device.

3 Claims, 3 Drawing Figures This invention relates to ayarn sensing device and particularly to such a device cooperating with other arrangements such as an automatic cutting arrangement.

During their making or their treatment, the yarns are displaced and may break. For instance, during the drawing operation the yarns may break because of the unevenness or momentary higher tension exerted on filaments.

Yarn. sensitive devices that are commonly known to sense breaks that occur are generally spring loaded and they exert a tension of about grams which tend to damage filaments and to further create unevenness of the physical properties of the product. Another group of yarn sensitive devices that is known are magnetically operated, but those known magnetic devices available to the public and which exert tensions of even less than a gram lack stability in the sense that they are very sensitive to noise or strong fibres, or heavy deniers.

The expression yarn are used throughout the disclosure and the claims is meant to include filamentary products, threads and other yarn-like or thread-like products, rovingand other fibrous strands, and bundles thereof, wire, string, twine, strands and the like.

There has now been found a simple sensing device which exertsvery little tension on filamentary products but which creates an increasedtension'when breaks occur.

Broadly stated the sensing device comprises:

a. in space relationship to a yarn, a yarn sensing arm,

b. said arm being rotatably mounted on a pivot,

c. in cooperation with saidarm a load easily displacable with respect tosaid pivot, so that at its normal position said arm in the presence of a yarn exerts a negligible tension on it, but in the absence of a yarn the load gradually shifts awayfrom said pivot thereby causing gradually increasing displacement of said arm.

In this broad application the arm is used as a visual detector and may be preferably coloured to more easily detect the breaks.

However, in a preferred embodiment the sensing device comprises a. in space relationship to a yarn, a yarn sensing arm,

b. said arm being rotatably mounted on a pivot,

c. in cooperation with said arm a load easily displacable with respect to said pivot, so that at its normal position said arm in the presence of a yarn exerts a negligible tension on it, but in the absence of a yarn the load gradually shifts away from said pivot thereby causing gradually increasing displacement of said arm.

d. said arm, said displacable load and pivot forming a rotating portion,

e. a switch means operatively connected to said rotating portion.

Still in another embodiment of the invention the sensing device includes at least one stopper means and- /or holding means to ease manipulation as will be described at greater length hereinbelow.

In an embodiment of this invention the load is so arranged that in the absence of a yarn it gradually shifts away from said pivot in a cycloidal fashion, i.e., by forming a cycloidal path.

In another embodiment the sensing device comprises a. a yarn passage,

b. in space relationship to said yarn passage a yarn sensing arm,

c. said arm being rotatably mounted on a pivot,

d. in cooperation with said arm a load easily displacable with respect to said pivot, so that at its normal position said arm in the presence of a yarn exerts a negligible tension on it, but in the absence of a yarn the load gradually shifts away from said pivot thereby causing gradually increasing displacement of said arm,

6, said arm, said displaceable load and pivot forming a rotating portion,

f. a switch means operatively connected to said rotat ing portion. I In the drawings which illustrate the invention,

FIG. 1 is a side view of a yarn sensing device,

FIG. 2 is a face view of the yarn sensing device shown in FIG. 1, the face of the frame being transparent for sake of discussion,

FIG. 3 is a schematic view of a yarn sensing device positioned on a yarn stretching and twisting or spinning apparatus.

Referring now to FIG. 1, number 10 designates a frame having the face portion 10a and side portion 10b. A mounting is provided with a tack welded screw 12 secured to side portion 10b. The screw 12 is adapted to conveniently fit a slot provided in a frame of the stretching apparatus or other apparatus. Other mechanical expedients may be used to secure the frame 10.

A substantially frictionless pivot 14 is rotatably mounted on bushing 16 held by a support 18 passing through face portion 10a and secured thereto. One end of said pivot 14 is provided with an L-shaped yarn sensing arm 20. A cam 24 is secured on the other end of the pivot by screw 26. A container 28 which contains a slidable load, preferably a rotatable ball of heavy metal 30, is mounted on the cam 24 by means of a brace 34 and nut 36. The container is also provided with a lid 32.

In space relationship to said cam 24 and fastened in the rear of the face portion 10a of the frame is a switch 38 having an operating arm 40 which may be actuated by the cam 24.

As shown on FIG. 2 the container 28 is oriented so that at the normal (in this case nearly vertical) position of the yarn sensing arm 20, that is when the arm 20 is in the presence of a yarn, most of the weight of the ball 30, or the load, rests on pivot 14. In the absence of a yarn the weight gradually shifts away from the pivot 14 thereby causing gradually increasing displacement of the arm 20. In a preferred embodiment this gradual displacement is cycloidal. Simultaneously the cam 24 actuates the operating arm 40 of the switch 38 shown on FIG. 1. The ball or load 30, the pivot 14 and the cam 26 may be called the rotating portion or rotor with respect to the frame 10 which may be considered the stator.

Preferably a first stopper 44 is mounted on the face of a frame 10 in order to reduce the path traced out by the arm when the yarn is cut.

The stopper 44 may also be adapted so that the yarn sensing arm 20 forms a yarn catching, grasping or cutting means. The yarn sensing arm 20 in contact with the stopper may be provided with knurling 20a for cutting yarns and the stopper may have a flat portion 44a, with or without knurling. At the normal position of the yarn sensing arm 20 the yarn is not in contact with the knurling 20a but should the yarn break, the knurling catches the yarn and holdds it in between the knurling 20a and the stopper 44.

The device is also conveniently provided with a guide or yarn passage such as pigtail 46 mounted on frame to confine the yarn to a given region with respect to the yarn sensing arm 20. Other mechanical expedients may be used if desired.

In order to ease manipulation of the yarn sensing arm 20, a handle may be provided such as in 42 screwed on the pivot 14 which is threaded at 14a.

Also a magnetic holder may be conveniently provided to hold the yarn sensing arm when the yarn is inserted into the pigtail 46. This magnetic holder has a magnet 54 secured to the side frame 10b, and cooperating therewith a ferro magnetic plate or arm 56 is positioned with respect to the magnet 54 and is held by pin 57 which is itself secured into the cam 24. This magnetic holder serves as well as a second arm stopping means to narrow the arm path.

If desired, other mechanical equivalents, such as a spring holding cam may be used instead of the magnetic holder.

Referring now to FIG. 3 a yarn 60 which may originate a yarn source 58, for instance spinnerettes, is allowed to pass along an automatic cutting ddevice 62 (for instance a CA 9-TC available at Telemecanique, Montreal, Quebec) having U shaped members 63-64, and to a guiding pigtail 65 to be pulled by driven roller 66 and idler roll 68.

At this stage the yarn is drawn by a set of rollers having feed roll 70 and a separator roller 72 and at the other end drawing roll 74 and separator 76. After the drawing operation, the arm sensing device 20 provided with the yarn guide 46, senses any break of yarn which may have occurred during the drawing process and before the twisting or spinning operation where the yarn is finally wound onto a bobbin 78 with the use of a ring traveller or twisting ring 80.

The switch 38 (shown in FIG. 2) is connected to the cutting device 62. If a break of the yarn 60 occurs, the arm 20 is displaced clockwise by the weight of the ball of heavy metal (or the load) 30 which moves cycloidally and counter clockwise and the operating arm 40 of the switch 38 becoming in contact with the cam 24, immediately feeds to the cutting device the signal whereby the yarn is cut at the cutter level by U-shaped number 63. Also the knurling 20a co-acting with the flat portion 44a cuts the yarn 60 thereby preventing unwinding of bobbin 78 onto roll 74.

With a plurality of apparatus described above, an operator can easily detect those yarns which are not running properly by merely checking the position of the yarn sensing arm 20. In this way also the yarn 60 is stopped from moving and thereby it prevents accumulation on rolls 70, 72, 74 and 76 of yarns, or molten yarns when the rollers are heated. Thus this invention eliminates yarn wrapping on stretching rolls and simultaneously eliminates a safety hazard. For instance in the past as this apparatus cannot be stopped for doffing or wrap removal because the yarn fuses on the heated rolls, severe laceration of fingers have been experienced while removing a wrap from the draw roll. By this invention waste has been reduced by at least 1 percent, efficiency has been increased by at least 15 percent. Also due to the very light tension (which may be in the order of a few grams in comparison to 10 15 grams exerted by other known twisting devices) there is no significant break of the yarn due to the yarn sensing arm 20 and yet this device is not over-sensitive.

Although this device for sensing yarn has been described with particular reference to a drawing operation, it can be easily seen that such a device can be used on any continuous operation where yarns are subject to break such as in spinning, dyeing, crimping, false twisting operations and the like. If desired, this device can also be used as a visual detector without the use of the cam and the switch.

It has also been found that the yarn need not touch the yarn sensing arm 20 as the air turbulence created in the vicinity of the yarn may suffice to generate an air cushion which exerts the necessary tension on the yarn sensing arm 20 to stay in its normal position. The sensing arm does not tend to exert pressure or tension on the filaments nor touch them as when spring loaded arms are used. Also the tension exerted on the yarn does not vary as is generally the case with these spring loaded arms.

The embodiments of the invention in which an exclusive property or privilege is claimed, are defined as follows:

l. A yarn sensing device adapted to exert a light tension and little friction on a yarn, said device comprising:

a. a frame,

b. a substantially frictionless pivot mounted through said frame,

c. a yarn sensing arm mounted on said pivot,

d. a cam mounted on said pivot positioned with respect to said sensing arm,

e. a switch mounted on said frame and operatively connected to said cam and said arm,

f. a tubular container mounted on said cam with respect to said arm,

g. a heavy ball shaped load confined and displaceable within said container, so that the load is off center of said pivot and preferentially rests on said pivot and the container is upwardly inclined when the sensing arm is normally touching a yarn, and said container is downwardly inclined in the absence of a yarn on the sensing arm,

h. a first stopper for said arm to rest in the absence of a yarn,

i. a ferro magnetic arm rotating with said pivot,

j. a magnetic force to lock said ferromagnetic arm and thereby said sensing arm when said sensing arm is displaced away from its normal position and from said first stopper,

k. said sensing arm being provided with a gripping portion adapted to cooperate with said first stop- 2. I'he yarn device as defined in claim 1 wherein said arm is L-shaped.

3. The yarn sensing device as defined in claim 1 wherein the load shifts away from the pivot by forming a cycloidal path. 

1. A yarn sensing device adapted to exert a light tension and little friction on a yarn, said device comprising: a. a frame, b. a substantially frictionless pivot mounted through said frame, c. a yarn sensing arm mounted on said pivot, d. a cam mounted on said pivot positioned with respect to said sensing arm, e. a switch mounted on said frame and operatively connected to said cam and said arm, f. a tubular container mounted on said cam with respect to said arm, g. a heavy ball shaped load confined and displaceable within said container, so that the load is off center of said pivot and preferentially rests on said pivot and the container is upwardly inclined when the sensing arm is normally touching a yarn, and said container is downwardly inclined in the absence of a yarn on the sensing arm, h. a first stopper for said arm to rest in the absence of a yarn, i. a ferro magnetic arm rotating with said pivot, j. a magnetic force to lock said ferromagnetic arm and thereby said sensing arm when said sensing arm is displaced away from its normal position and from said first stopper, k. said sensing arm being provided with a gripping portion adapted to cooperate with said first stopper.
 2. The yarn device as defined in claim 1 wherein said arm is L-shaped.
 3. The yarn sensing device as defined in claim 1 wherein the load shifts away from the pivot by forming a cycloidal path. 